Add v0.1.3 backend features: metadata fields and search

Backend Changes:
- Add estimated_minutes field to tasks (stored as integer minutes)
- Add tags field (JSON array) for categorizing tasks
- Add flag_color field for visual priority indicators
- Add search endpoint (/api/search) with project filtering
- Update JSON import to handle new metadata fields

Frontend Changes:
- Display version v0.1.3 in header
- Add search API client function
- Add format utility for time display (30m, 1.5h, etc.)

Example Data:
- Update example-import.json with time estimates, tags, and flags
- Demonstrate nested metadata inheritance

Note: Frontend UI for displaying/editing these fields in progress

backend/app/schemas.py

@@ -11,6 +11,9 @@ class TaskBase(BaseModel):
     status: TaskStatus = TaskStatus.BACKLOG
     parent_task_id: Optional[int] = None
     sort_order: int = 0
+    estimated_minutes: Optional[int] = None
+    tags: Optional[List[str]] = None
+    flag_color: Optional[str] = None
 
 
 class TaskCreate(TaskBase):
@@ -23,6 +26,9 @@ class TaskUpdate(BaseModel):
     status: Optional[TaskStatus] = None
     parent_task_id: Optional[int] = None
     sort_order: Optional[int] = None
+    estimated_minutes: Optional[int] = None
+    tags: Optional[List[str]] = None
+    flag_color: Optional[str] = None
 
 
 class Task(TaskBase):
@@ -74,6 +80,9 @@ class ImportSubtask(BaseModel):
     title: str
     description: Optional[str] = None
     status: TaskStatus = TaskStatus.BACKLOG
+    estimated_minutes: Optional[int] = None
+    tags: Optional[List[str]] = None
+    flag_color: Optional[str] = None
     subtasks: List['ImportSubtask'] = []